He was filmed committing the sex acts on the baby the day after Lostprophets’ final album Weapons was released.

Watkins appeared on BBC Radio 1 just hours before the incident in April last year.

The baby's mum, Woman A, admits aiding and abetting the attempted rapes on her son.

She also admits sexually touching the child and taking photographs of herself carrying out a sex act on the child before sending the picture to Watkins.

The court heard texts he sent to her talked of a "summer of filthy child porn." He also discussed using the baby as a "sex slave".

Watkins also admitted conspiring to rape and sexually touch the daughter of the second fan.

He admits aiding and abetting Woman B to touch her daughter while he watched on Skype.

Mr Clee said: "They had a camera session where the woman sexually assaulted her baby at the direction of Watkins. It is a 45-minute video.

"The baby is wearing a nappy which is later removed."

He described how both people committed sexual acts during the filming.

An earlier court hearing was told police had 72 pages of conversations between the pair online talking about their sexual relationship.

Woman B mentioned she had a daughter of a young age and Watkins said: "Bring her along as well."

She said she was getting the child ready for their meeting together - and "what they all will do together" when they meet up.

The prosecution said the investigation led police to discover Woman B and Watkins had met at hotels twice in and around Cardiff.

She admits sexual assault after touching the child, she also admits taking an indecent photograph of the child before distributing them.

Watkins also admitted three counts of possessing indecent photographs of children.

Mr Clee said the images were found when police searched his home in Pontypridd.

He said: "Images were found on a secret hard drive. It was later sent to the GCHQ where they crack passwords. They found his password was "If***kids".

"He had two other videos he made of him having sex with young fans."

The court heard that when Watkins was investigated by police, they found a bag of crystal meth. He had also talked about taking crack cocaine.

Mr Clee said: "Controlled drugs played a significant part in this offending. He used drugs while abusing children and talked about using drugs to facilitate the abuse of children."

He talked about giving drugs to children and one of the abused babies had tests showing she had been "exposed" to crystal meth.

Watkins admitted taking indecent photographs of a child dating back to 2007 - 10 months after Lostprophets released the biggest selling song Rooftops.

The song got to number 8 in the UK charts - making it their most successful single alongside 2004's Last Train Home.

Watkins also admitted taking indecent photographs in 2008.

The singer, who has sold more than 3.5million albums with the Lostprophets, had denied all allegations and claimed he was a victim of a "conspiracy to frame him".

But Watkins, who waved at a group of young people in the public gallery, changed his plea on the day his trial was due to start.

Sally O'Neill QC, defending, said: "His position is still the same and he says he cannot remember the events depicted in the videos."

Watkins argued that it was possible the videos might have been electronically altered. But he dropped his defence after legal argument.

Miss O'Neill said: "He has had expert advice from computer experts and because of this he is now in a position to change his plea."

Judge Mr Justice Royce is expected to sentence next month.

The judge discharged the jury and said: "You all have been saved from having to watch some extremely graphic and distressing material."

After the hearing, Detective Chief Inspector of South Wales Police Peter Doyle said: "We believe Watkins may have other victims around the world and our investigations are not over.

"This investigation has uncovered the most shocking and harrowing child abuse evidence I have ever seen.

"There is no doubt in my mind that Ian Watkins exploited his celebrity status in order to abuse young children.

"Today's outcome ensures that the three people responsible have been brought to justice.

"Two very young children have been removed from this abuse and given a future that would otherwise have been denied them.

"The safeguarding of children has been the primary objective of the investigation team and the outcome of this investigation has been achieved through a multi-agency approach at international level."

DSI Doyle said it was an "extremely complex" investigation with evidence being taken from witnesses around the world.

"A significant amount of electronic data has been retrieved from computers and web-based storage which has provided crucial evidence to support the case.

"We have worked in partnership with Interpol, other police forces, national crime agencies CEOP command, local authorities in England and Wales, the Dept of Homeland Security in the USA, and the NSPCC.

"Today's outcome does not mark the end of our investigations and we will work tirelessly to identify any other victims or witnesses and seek the justice they deserve.

"Above all this investigation has been focused on the protection of children and my thoughts today are with those victims."